Page 814 - Advanced_Engineering_Mathematics o'neil
P. 814

794    APPENDIX A A MAPLE Primer

                                 out the operations. For example, to add 16/37 times < 1,−5,3,−9,−22 > to 15/92 times
                                 < 0,3,−3,6,−1 >, enter
                                                                                  ∗
                                                   ∗
                                          (16/37) < 1,−5,3,−9,−22 > + (15/92) < 0,3,−3,6,−1 >;
                                    We could also name the first vector V and the second vector G by
                                                           V:=< 1,−5,3,−9,−22 >;
                                    and
                                                             G:=< 0,3,−3,6,−1 >

                                    and then compute
                                                                   ∗
                                                                                ∗
                                                          (16/37) V + (15/92) G;
                                    For the dot product of two vectors V and F (which can be n-vectors), enter
                                                             DotProduct(V,F);
                                    Here V and F can be defined previously or can be entered into the dot product command.
                                                                                                      3
                                    Unlike the dot product, for the curl of two vectors, we are restricted to vectors in R .Forthe
                                 curl of V =< a,b,c > and F =< d,e, f >, enter
                                                    CrossProduct(< a,b,c >,< d,e, f >);
                                 As usual, the vectors can be entered directly or they could have been previously defined.
                                    We can also carry out the vector calculus operations of gradient, divergence and curl. To
                                 begin, we will work in rectangular coordinates. Set this system by
                                                  SetCoordinates(‘cartesian’[x,y,z]);
                                    MAPLE expects the word cartesian in this command.
                                    For the gradient of a scalar field, use the del operator, which in MAPLE is called del or
                                                                                          2
                                 nabla. For example, we can define the scalar field f (x, y, z) = xyz − xy cos(z), by entering
                                                                                    ∗
                                                                      ∗
                                                                        ∗
                                                                                      ∗
                                                     f:=(x,y,z) → x y z-x+4 y z;
                                    Now compute the gradient of f in any of the following ways:
                                                           Gradient(f(x,y,z));
                                    or
                                                              Del(f(x,y,z));
                                    or

                                                             Nabla(f(x,y,z));
                                    or
                                                                  ∗
                                                                             ∗
                                                                               ∗
                                                          Del(x y z-x+4 y z);
                                                                ∗
                                    or
                                                                               ∗
                                                                                 ∗
                                                                   ∗
                                                                 ∗
                                                         Nabla(x y z-x+4 y z);
                                    To work with divergence and curl in rectangular (cartesian) coordinates, we can first enter
                                 the vector fields of interest. For example, to enter the vector field
                                                         F(x, y, z) = xyzi + (x − y)j + yzk,


                      Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
                      Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.

                                   October 14, 2010  15:43  THM/NEIL   Page-794        27410_24_appA_p789-800
   809   810   811   812   813   814   815   816   817   818   819